Small bump on left testicle with increasing pain.

I'm 24 years old and I'm having some real problems here. For the past few months I've had a very discomforting feeling in my left testicle. I didn't think anything of it for awhile until just tonight I noticed a small bump on it.
When I push on it it really causes discomfort. A sharp pain that I not only feel in my testicles, but also down my leg, and even in my stomach. It actually even makes me feel nausious, and fatigued. I'm so torn on what to do cause I can't see a specialist, they're too expensive. And I've been to the ER and had an ultrasound done, they didn't find anything. Except the bump they could feel themselves.
I'm really starting to get stressed over it, and very nervous. Anybody have any idea what this can be? Any advice what to do to find out?
I'm a broke joke... PLEASE HELP!!