You don't have a UTI, and cranberry juice will NOT treat a UTI if you have one. Total myth. It's only for prevention, not treatment. Men don't get UTIs unless they stick something in their urethra, have a structural defect, or are trapped in soiled underwear.
The "veins" you find irritated could be actually lymph channel irritations, however they would not be blue. This would go along with the lump (possible lymph node inflammation), and the raised feeling of these channels under your skin. The red markings could be an allergic reaction, or just a symptom of general irritation related to whatever caused a lymph reaction.
No, it doesn't sound like an STD.
Unfortunately, if you did go to the E.R. you wouldn't receive any help. They treat emergencies, and know about as much about penises as you know about breeding silk worms.
Insurance is NOT required to see a urologist. And the doctor's office will work out payment with you. An office visit should be less than $200, and can be put on credit or payment plan. You only get ONE penis, and it's been through a lot recently, so I suggest you get it some proper care before there's actual damage that could have been prevented with prompt attention.
This is one of those things that a visual inspection tells so much more than a description. And a general doctor isn't going to be worth your time and expense compared to a urologist (no more expensive, but all the expertise).
I respect that you are attempting to make the best of a situation without rushing to the doctor, but I think it's gone beyond a lay-person's help level and you do actually need to see a urologist at this point.