possible convergence insuffiency?

[dmci]

for the last 3 months i've been experiencing throbbing/tingling pulses in my forehead behind my eyes. these come in pulses like a heartbeat but there is no pain. its almost like a migraine or headache with no pain at all. reading/focusing on something nearby makes this a lot worse - the throbbing and pressure increases but again with no pain. after a while this begins to make me dizzy and and some occasions has made me nauseous and sick. looking in the distance seems to help this. and also covering one eye seems to help. i have no problem driving for instance.
my first thought was vertigo but my doctor was not convinced as he said i would be struggling to keep my balance. he gave me an anti vertigo prescription but this had no effect.
I visited my optician and he dropped the prescription of my glasses (i am short sighted) to see if this would help and it seemed to work for about 2 weeks but then the throbbing returned. After going back to my opticians he suspected convergence insufficiency. he had me do some pencil push ups and although i didn't experience extreme double vision, the pencil was quite blurry when within 3-4 inches of my nose. i could also feel a painful strain or tiredness in my eye muscles. the optician said i should be able to do this without feeling any strain. he prescribed 5 sets of pencil push up twice a day for the next month. If no improvement following this i would need to get prisms installed in my glasses
Does this sound like convergence insufficiency to anyone? i would like to be sure it is rather than wait a month while i could have been pursuing other possible causes. I am a 30 yo male with no significant health problems. my doctor has performed blood pressure and blood tests and all these came back negative

[Ray T Oyakawa, MD]

3 to 4 inches is very close.  This could be convergence insufficiency or you need stronger glasses.

Dr. O.

[dmci]

but when i wear my old glasses which have a stronger prescription it feels worse