I have constant pain in my lower ab & groin area for 1 1/2 years now, done all tests, nothing came up. Could it be a nerve related problem?

Possible. You may be right. Detailed sensory examination and perhaps diagnostic nerve blocks may shed light.
Interference fields. Make sure you do not have scars or trauma in midline. If you have a habit of carrying cellphone near that area can be due to emf fields. If due to scar or trauma castor oil packs with kinesio taping will help. If due to emf buy qlink products to protect your energy fields.
? Femoral neuralgia. Femoral/ inguinal nerve pain likely. Difficult diagnosis, difficult treatment. Consult with a pain specialist please.