What Causes Reddish Bump On The Leg Oozing Watery Blood?

Im a 24 yr old caucasian female 5'8 130 lbs. Fit and on no meds. I take vitamins daily and on no birth control. I have had a child 3 years ago, my gall bladder removed 2 1/2 yrs ago. I have recently developed a red lump on my leg (below knee mid calf) about 1/4 inch big. its swollen very sore (in fact the muscle around it is sore) and very hot to the touch. a day and half ago i thought it was a mosquito bite (it kind of itched like one and was tiny and swollen like typical mosquito bite) and have tried squeezing it to see if any puss would come out and maybe relieve some of the pressure but just some orangish liquid (like watered down blood) came out...can anyone help tell me what this is or what to do?