Constant cramping

I wasn’t sure where to post this but I need advice

(I’ll try to make this as short as possible )

I have constantly been cramping for 2 months now .. my periods come on regularly .. no pain when I pee or have sex No STDs , negative pregnancy tests ..

I’m hoping to get an ultrasound tomorrow at my appointment to see if there’s something going on down there but I’m extremely nervous 😟

I do not cramp for the 5 days I am on my cycle .. so I cramp between periods. My doctor is just as confused as me.

I did take a plan B pill December 28th but my doctor said that is not the reason i am constantly cramping.

The cramps got so bad last night that I was so uncomfortable 😣 it lasted for 4 hours

The cramps come and go throughout the day ( on a pain scale going from a 2-9 )

My mom just told me that her and my grandma both had endometriosis but my periods are regular , I do not cramp at all so I can’t have bad cramps nor is my bleeding out of the ordinary ...

My doctor kept asking me questions trying to figure out what it could be but she can’t figure it out.

Has anyone had this before ?

Oh and I’ve never had any kind of surgery 🤷🏻‍♀️😕