There is one case on record of someone nearly dying from an injection of 40 mg of DMT. Symptoms included tachycardia, a rapid fall in blood pressure, extreme cyanosis, and auricular fibrillation. This lead to cardiac arrest, but the test subject was saved via vigorous cardiac massage.
So in short, DMT would have likely killed the test subject had the subject not been revived. The subject's heart stopped beating.
I would NOT go deep into it if you're experience those kinds of side effects from it.
The safety of smoking DMT is unknown. With at least one near fatal incident on record from injecting 40 mg of DMT, I would be VERY CAUTIOUS going in deeper with the symptoms you described.
DMT is actually quite toxic. The LD50 for DMT is lower than bufotenine. Bufotenine has a bad reputation because of it's known bodily side effects when injected, but all lab tests show that DMT is actually more toxic. The only time bufotenine ever showed toxicity that was close to that of DMT was when it was administered to test subjects along with chlorpromazine.