I have a small hard bump on the back of my hip for over a year now (causing me no problems) and yesterday it was red and irritated.. what could it be?

Needs to be checkecd: It is very hard to say what it could be without examination . It could be a cyst, a fatty tumor , or something else. Since it is red and irritated, I suggest that you have it checked by your Family Physician

Cyst: one of possible diagnosis of some bump that becomes inflamed is Sebaceous cyst that got infected; have ur family doctor take a look and consider evacuation of the whole thing, rather than just lancing and short antibiotic course; ur doctor should be able to make diagnosis easily. meanwhile some warm compress may offer some benefit; Good luck

See a Dermatologist: 19 y/o Female says, I have a small hard bump on the back of my hip for over a year now (causing me no problems) and yesterday it was red and irritated. What could be? Simple answer is See a Dermatologist to be sure. In general anytime a stable skin rash/ lesion changes in color/shape/ appearance/ form or behavior it should be evaluated by a knowledgeable Consult.