Lower back pain

It’s been 5 months I haven’t had my period. Had spotting last month for 10 days then after 17 days again 3 days spotting. Severe back pain and lower abdomen pain nauseous had to take a day off went to gp 2-3 times for not having periods and they are trash. They don’t even want to listen to my problem and want to give me codien without assessing my problem I told them I might be pregnant. they said take birth control to regulate period. I am completely heart broken I don’t want to end up getting endometriosis, ovarian cyst or anything else. I am so lost.