Squishy bump in between my butt crack??!!?

i am 16 and am having this butt crack problem which is becoming unbarable.I have had it for about a good 14 days, but at first it was hard until my sister poked it and a clear white-ish liquid and a little little bit of blood came out. i cant sit or lye down unless its on my stomach. it hurts SOOO bad. At first it was hard but now its squishy.It's so tender and i cant even touch my upper hip without feeling the sting. What should i do? And if i do go to the doctor how long does the lancing last? also how long will it take to fully heal? thanks