At 5 Weeks I Tested Positive To A Home Pregnancy

At 5 weeks i tested positive to a home pregnancy test few days later i started bleeding and having really tense cramping yet didn't pass anything, I still had a few pregnancy symptoms after that, went to the docs do to some tests they came back negative both blood and urine, then recently I had my "second period" it was really heavy then usual, with the same tensed cramping but not so bad i passed a few clots probably the size of a finger nail. few days before my second period i noticed a lump on my left abdominal, it'll come and go its tender at times. I recently went to the doc a few days ago came back with a negative urine, they didnt test my blood. Should i have asked for ultrasound, they had never tried to do a scan when they first dimissed my miscarriage, nor did they try to do a scan this second time. what could be wrong? I know my body and something is not right. Seen 3 docs so far and they said the same thing.