20 days after inguinal hernia surgery. right testicle very sore to even touch. pain near where mesh is fixated. normal or should i worry?

Depends: It is not uncommon to have discomfort after an inguinal hernia repair for several weeks. In fact you probably won't feel completely back to normal for 6 to 8 weeks. If the pain is getting worse or not getting better at this point you should be seen by your surgeon for follow-up evaluation. If there is no redness or drainage and the pain is getting better over time it may be safe to watch.