If the pain is bothering and worrying you that much, call the doctor. They will either make you an appointment for today or send you over to L&D to be checked out. With stuff like this, it needs to be checked out. Abdominal pain could mean something as bad as placental abruption or preterm labor or be something as mild as Braxton Hicks contractions. Definitely go in asap, today, and keep us updated! :) It's better to be checked out, but if it makes you feel any better, I bled at 28 weeks and freaked out, turns out i had a UTI (no other symtpoms lol) and my daughter is now 2 and a half.
I am 35 weeks as well experiencing similar symptoms. Most likely Braxton hicks but you never know. This is my first and my obgyn said to moniter the pains and contractions cuz I could gp early. Make sure to time them. You will be going into labor in the near future hun!
Did your doctor do any follow up checks for a UTI after finishing the antibiotic? It's always a good idea to do another test after, plus- during pregnancy you can have a UTI without any symptoms.
It's hard to say what the pain might be- so many abdominal pains happen during pregnancy- I wouldn't hesitate to call your doctor, especially if you just feel like something isn't right.
Let us know how you are doing!