Shortness of breath, barking cough, swollen lymph nodes

Hello,

I am a 22 year old female...I have been having progressively worse shortness of breath with activity (I used to climb the stairs to my office every day, but now I can barely make it up one flight without stopping to catch my breath), I have had a barking non-productive cough for the past two months (the cough is increasing in frequency), I get dizzy and my heart pounds when I stand up, my blood pressure was so low yesterday that the nurse couldn't get a reading, my resting heart rate is increased (110 bpm). I also have a swollen pea-sized lymph node just above my left collar bone, a grape sized one below the left side of my jaw and another pea-sized one under my chin; they are all very firm (like a rubber ball) and minimally mobile. I am also VERY pale, you can see the veins in my chest, arms, hands, feet, legs, etc and there are huge dark circles under my eyes. There are also a few lumps in my left breast, but my doctor cannot tell if they are lymph nodes or not.

I have been having episodes of extreme drenching sweats at random intervals, and I have lost 50 lbs in the last 5 months without trying.

I am also having problems with vaginal bleeding and pain during and after intercourse, in the past month I have been bleeding bright red blood for two weeks (with some clots) and in the past two weeks it has switched to brown blood with clots; there is no smell, I am in a monogamous relationship (and have only slept with one person in my life), and I have never had an STI. Recently I have begun having nosebleeds as well.

I am also very fatigued, I never feel rested and if given the opportunity I will sleep for 16-18 hours at a time. NOTHING helps my feeling of fatigue. My PCP feels that I may be depressed but I don't agree, I WANT to socialize, play with my daughter, run, cycle, and do everything that I used to do and I still thoroughly enjoy all of those activities, it's just that I have to take frequent breaks to sit down/cat nap because I get so tired I just can't keep up...

I had a chest x-ray and was told that I have a "cloudy area" in my left lung, and I am currently awaiting the results of a CT scan.

I am currently being evaluated by my PCP, but she isn't taking the situation too seriously because of my young age (she feels that it can't be anything serious because I am young and was previously healthy)...I have been tested for mono (EBV), cytomegalovirus (spelling?), AIDS, Hep B and C, TB, and a type of herpes virus (can't remember the name of it), and everything was negative. I have also been tested for every STI in the book (which I felt was unnecessary and insulting given my sexual health history), everything was negative with that as well...

...before all of this started I was perfectly healthy, full of energy and running 10K nearly every day...this is really affecting my quality of life and interrupting my daily activities and I am desperate to know what might be wrong with me?? If anyone can help, I would be extremely grateful!