I have a red swelling on my lower left buttock. A bit like a mosquito bite but it felt stiffer. Its tender to touch, very itchy and its mild throbbing pain (maybe because of the area, its right where I sit). It have a black raised dot in the middle(on the beginning, its only red itchy bump and it got firm later on). Not pointy, just smooth and feel like there is liquid underneath. And I accidentally popped it, watery blood came out. I put disinfectant cream and seal it with plaster.(should I done that?)Please give me an answer, any pointer will be gladly appreciated.