Lips turning red is NOT necessarily a sign of an allergy. Mine turn red after 5 minutes of play too. That is because of a light irritation (trumpet playing is not "natural") and blood flowing. A bit of pain after a while is also not necessarily a sign of an allergy. Excessive burning and swelling together are signs of an allergy. Only your doc will know for sure. I won't play on raw brass mouthpieces. The silver or gold plating must be intact too. No sense in taking a chance on anything. Once you start having chop problems, there is a psychological barrier for the rest of your life. It ain't worth it! You can tape the mouthpiece to your arm overnight to see if there is a reaction. It may not be scientific, but you would be at least a step closer. You can also put the mouthpiece on your lips with little pressure for 30-60 minutes WITHOUT playing and see if there is a reaction (you can read a book or watch TV at the same time). I would not invest in ANYTHING without knowing what is up. You have no money for a doc, but can afford another mouthpiece. Doesn't sound like a good plan to me. If you have a "heavy" playing scedule, what you describe can be simply a sign of too little preparation/practice time to support that schedule.