endo pain to the right of belly button?

since november, before my period every month i’ve been getting weird tugging, shooting pains near my belly button. it’s not horrifically painful, just very uncomfortable. it comes and it goes throughout the day. it feels like something is fluttering in there too. i’ve been concerned about something like appendicitis but it’s been four months. i don’t have any other symptoms of appendicitis. plus it’s much higher up in my abdomen than where my appendix should be. it’s so annoying and concerning! it doesn’t hurt when i press on it. once i get my period, the pain goes away completely until pms week. i don’t know if anyone else struggles with this weird sensation but let me know if you do!