It's not safe to take pain killers while your in first trimester as it could cause miscarriage. Best to wait until your a bit further along. I'm 6 months and have never took any painkillers
I'm a migraine sufferer whom before being pregnant took a daily prescription. For headaches my Dr. suggested a daily cup of coffee to ward them off if that didn't work 1 Tylenol every 6 hours as needed. Honestly I'm totally afraid of harming my baby so if I've taken 3 Tylenol in 32 weeks it's alot. Def ask your Dr or the front desk a list of meds you can take while pregnant they should have one readily available. I know Tylenol, Benadryl & Tums was on that list.
If you really need it, tylenol is safe every once in awhile. Don't take motrin, or anything with ibuprfin, it causes heart defects. What helped me most with backache was a simple prwgnancy exercise called pelvic rocking. It helps reposition baby off your back