lumps in multiple places

I am a 20 year old male and had a lump on my right testical on the inside since I was 12 and the doctor did an ultrasound and said it was nothing but my parents never really discussed it with me assuming it could have been bad I guess.
Now I have a lump the size of the tip of my pinky in my rectum and i've had it for about a year, but it does not seem to be attached to any muscles. I do excrete blood at least once a month, and now I have developped a very painful lump under my left armpit that is attached to my muscles as it hurts when I flex. I am very itchy when I shower in hot water and when I itch it leaves marks. I have lost about 25 pounds in 2 or 3 months. I also have a fluctuating appetite, where one minute I am really hungry but if I wait I feel full and can't eat. I have had also for about a year now continuous neck pain where I have to crack my neck to get it to go away but comes back after 5 minutes. I am worried this is tied to cancer and really would like an opinion before I visit the doctor.