I'm having problems with my health. Please help!?

Even thought it probably isn't serious at all, I feel like my body's falling apart. Over the course of the last two months, I've had the swine flu, strep throat and now sick with what feels like my third cold. I've been really sick and worn out. I don't know why my immune system is so weakened. I eat healthy, exercise when I'm not sick (which hasn't been often lately) and take my vitamins. I took antibiotics when I had my strep throat so I'm uming it cleared up since the sore throat is gone. Last night I discovered a golf ball sized lump on the back of my head. I'm thinking it's just a swollen lymph node since I have a lot of pressure in my sinuses from being completely congested. My left elbow has very sharp pain in the joint when I try to straighten out my arm. I've had the pain for three days, it was sudden but comes and goes for a couple of hours. I've been totally depleted of energy and I can't get out of bed if I can help it. Should I go to the doctor? I'm kind of hesitant because I've had some problems with my insurance and I'm still working out the kinks. I don't want to go if I can avoid it, especially if all they can do is tell me to wait it out. What could be going on with my body? Could I still have strep throat and now getting rheumatoid arthritis? What's going on????? I'm so sick of being sick! It's depressing. Any info would be great.. I've spent some time researching on the internet but nothing seems to match all my symptoms.