Missed period, cramps, weight gain, painful ..what's going on?

Its been 10 days since I missed my period. I don't have the spot on regular periods but they only delay by 2-3 days max. I took the pregnancy test and its negative. My other symptoms since last 4-5 days include pain in the pelvic area including intermittent cramps in the lower abdomen and ongoing back ache. It gets worse with exercise. Today I also have pain in my right leg. My mood swings are disastrous. I sometimes also get pain in my . has always been painful for me. I'm surprised because I get and I don't think I have the dryness issues. No infection nothing. Is it just the hormonal imbalance? I've gained weight in a month. I'm not sure what's going on. I could get the doctor's appointment only after a week. Am I doomed?