I have been having an average of 80/60 BP, with a heart rate of 115. I woke up today with my heart racing, and I felt freezing cold. I went from sleeping 3 to 4 hours a night to around 16 to 18 hours, and I am only 20. The lowest I have ever recorded as my blood pressure was 65/53, and my heart rate was over 120. I fainted shortly after taking it. I told my doctor about what I feel is a serious problem, and he said it was normal. He sent me to another doctor for my sleeping problems and headaches. I also started having fainting problems right after I got off my shot, and I bled nonstop for over 3 months. It feels like my body has not yet gone back to normal.
You mentioned a shot but did not specify what it was. Because you also mentioned bleeding since you stopped the shot, I presume you are a female and went off of a birth control shot? I am not certain that fainting, low blood pressure, and fast heart rate are normal symptoms after going off of any shot. With your continual bleeding, it is possible that you are anemic, and your cardiac symptoms certainly describe some sort of issue, perhaps an arrhythmia of some sort.
Here are some links that might help you learn about what is happening with your body:
Understanding Low Blood Pressure
What Your Blood Pressure Should Be
What You Need to Know About Birth Control
I strongly encourage you to go to the emergency room as soon as the symptoms start up. (Go now if they are continuous!) While it may not end up being serious, this certainly does not sound normal and you should seek treatment. Only a physician can diagnose and prescribe treatment for the issue.
Best of luck,
Monica M. Skidmore, MS, RD