Randomly getting bug bites!!!!!!!!!!!?

ok so i have just (today) gotten alot of bug bites, im not going to go over all of them, but just the onesthat im concerned with. well first, there are two on my back that are very close to eachother and are big red bumps (about an inch in diameter) and one is smaller than the other. i think they are bed bug bites but im not sure. now the one that im really concered with is the one on the left side of my shin. this things is FREAKING HUGE. i measured it and its about 3 inchs in diameter. it basicly looks like a kneecap(no joke) and has a little red spot in the middle but just mildly red. it has gotten incresingly bigger throughout the day. serious answers please dnt just tell me to call an extrermanator. yes i wash my sheets often but i have had my mattress for......8 years? almost? and i probably have had the blankets for even longer. im not rich, i live in a little apartment in escondido (san diego) and i see bugs alot but i have never gotten this many.....can someone explain to me what is on my shin??