The past few months I've been having really short periods which seemed really strange to me.And then this week my period completely stopped after not even 3 days.

I had a sinus infection so I got prescribed some anti-biotics and then like 6 hours after starting them my period started again and it's REALLY really heavy and painful.

Is this just normal or should I see a doctor? Does it have something to do with the antibiotics?

Are you on the pill? Antibiotics can interfere with the absorption of the pill and thus could cause it to restart.

if it has come on all of a sudden then it is probably for a reason, most likely the antibiotics. as for the previous weirdness, that may be something unrelated? i dont know if you have a good pharmacy where you are, but they may be able to advise if it is the antibiotics, or if you can't get a doc app soonish maybe ask if you can see the clinic nurse?

I have occasionally had really short periods that lasted only 3 days. That's nothing to worry about.

When I was on the pill my periods were super extra short like that...3 days or so. My first period after I stopped taking the pill was so fucking heavy. I agree with the others who said that it's likely the antibiotics interfering with the pill. Lots of girls go on the pill just for the tiny periods. Don't worry about it.