Guitar Playing, damaged ring-finger tip?

It is possible to do nerve damage by practicing too hard or too long, but this is usually spread out over all the fingers and it usually requires practicing more than 4-5 hours a day, for weeks. I suspect that you may be using improper technique and have an instrument that has action that is too high. If the pain and tingling continues than you should definitely consult a doctor. I also recommend that you have your instrument adjusted and consult a teacher so that you can be sure that you are not using an improper technique that may be interfering with your playing. (this is very common in self taught players and often results in poor technique which has to be "unlearned" before the student can progress)