Thank you for the report and I wish you safety, physically, emotionally, mentally and spiritually! You will be in my prayers!
This is something to consider for safety reasons, and I have had a can of whoop-ass opened on me psychedelically. I started off with Salvia 30x for my first psychedelic experience and have never been the same since. You can only integrate this experience, but for a long time, I felt like Salvia "attacked" me, with all the cultural stigma attached for "La Maria Ska Pastora". I have to give you a warning however, whether you want to become defensive or not:
Ever possibly wonder, past the intense psychedelic reaction and fast onset of the experience that, especially after experiencing the SAME exact physical symptoms of Choking after the 25mg x 2 test-run, that "FUCK, i might be having an allergic reaction to a tryptamine?" Yes, DMT is safe, FOR MOST PEOPLE. However, a very similar tryptamine, bufotenine, lead to choking-like symptoms who were, as I remember correctly, injected with the substance. you might have actually underwent a possible life-threatening physical allergic reaction (people have had heart attacks) and the nurses on the Spirit Molecule documentary even emphasized how happy they were to have a crash cart in the room. Seriously. We are entering the foreign and infinite waters of our psyche and not only that, the Spirit Molecule, can not only take one psychologically to the edge of death, but can take the unhealthy to the Physical edge of death, regardless of how much the "UK has had vast extensive research on the safety of DMT fumarate". One can easily become trapped in Maya (illusion). Say Hooray! You probably are not under attack. Entities exist, oh GOD, they do.. but you are not having an attack. Yes, there are entities. The Spirit World exists and constantly interacts and interpenetrates our third dimension. The likelihood of you being consistently locked out of "hyperspace" which is only a cultural connotation at best to explain the intense flow of information coming from the fourth dimension after smoking the extracted crystals of various plant materials that could biologically be using these compounds as a warning defense mechanism, rather for enlightenment. We might simply be enlightening ourselves by consistently kicking our asses. Some cultures practice self-flaggelation and whipping, so sometimes pain is desirable. Pardon the ramblings. 
If that wasn't an allergic reaction (and if it was, what might happen the third time?), then possibly, you are not physically prepared for the spiritual vibrational intensity of DMT. It's relative vibrational frequency which can be quantitatively measured in terms of Hz is probably vibrating at a rate higher than the human brain (which naturally vibrates at about 72 Hz, remember that, simply Hz). Now, Rose essential oil, the highest recorded and documented oil so far, had a vibrational frequency of 320 MhZ!. See, MEGA-Hertz. Plants are quantitatively higher vibrational beings than us. The admission of ignorance is beginning of the attainment of wisdom. At the moment, I recommend (after 5+ extensive years of occult and esoteric practice), you must work harder in the paths of every-day self sacrifice (THE RIGHT HAND PATH, Research it!, ego annihilation and overall self-realization. Rememeber, Ayahuasca and admixture plants are "power plants" in the culture, "teachers". Ayahuasca is work, smoked DMT is even harder work. Do you know how effortlessly strong of a psyche you must have to integrate the myriads of information that pass through you during a breakthrough? Overall, another thing to keep in mind is, you very likely had an Allergic Reaction.
If anything, if there is an entity, it is YOU, preventing YOU, your own EGO, from breaking through, and the Ego is what religions classify as Satan, the Great Adversary, etc. It knows the Sacred potential of DMT. But I want to Emphasize this. Really, Look. The fact that you CHOKED and were unable to expectorate really concerns me for your health with the substance! leads me to really let you know to consider the weight of what you're thinking about pursuing. Read "Why you should NOT Take DMT", if you haven't.
DMT might be "spiritual" but not every reaction is Spiritual. I know with all that others have experienced, it is easy to summarize or intuit that an entity might be "out to get you", but feel a lot safer knowing that you might have had an allergic reaction and aren't under the attack of possible Luciferian spirits. They aren't fun to play with. And remember, DMT is the third most powerful natural hallucinogen by weight under Salvinorin A and 5-Meo-DMT, so take that one in mind. Even 5 mg can elicit reactions in individuals, with 10mg yielding a breakthrough.
Also, with all this said, i wanted to say I am proud of you for actually going back and ever trying it again after the choking sensation. That would have skepted me out.
Love and Light
EarthDweller