I Have A Big Blister Looking Thing About Half The

I have a big blister looking thing about half the size of a dime on the inside of the top of my leg..groin area I guess...but it is right I side a stretch mark..I have had two kids the latest 2 months ago and I noticed it first about a month ago and I popped it and water and blood came back and I noticed today that it has came back and was kind of painful...should I be worried...note I bled 6 weeks postpartum and had to wear pads..