get a second opinion. if your body is telling you something's wrong, then there definitely is something wrong. my GP didn't take me seriously either, was in tremendous pain and he'd just give me antibiotics and pain killers every month. Neither worked. Went and got a second opinion and had my concerns taken seriously. Turned out i had a huge cyst which was close to bursting and was scheduled for surgery within a week. Upon further inspection i was diagnosed with endometriosis on my bowel, rectum, colon, spine and uterus. So, insist on that second opinion.

I agree, get second opinions if you feel you're not being taken seriously!

Be persistent and find a good dr. I went through a handful of drs before i found one that genuinely cares