Nothing can be said with surety without having a look at the lesions. These could be due to viral infection - human papilloma virus or present normally.
If they are not responding to medical treatment and have been present for such a long time it would be advisable to discuss with your doctor about cryotherapy, electrosurgery, keratolytics, contact immunotherapy, etc and what would be the best option in your particular case.
You should consult your skin specialist and get a clinical examination and clear out any doubts that you have.
Let us know what your doctor advises and post us if you need any other information.
Update us on how you are doing.