I wonder if some learned people on this forum could help me. My core system is wing chun, back when i was training i noticed that a lot of the deflections attack the inner forearm of the opponent with our hard outer forearm.

I used to some times train with out forearm pads on when i was attacking other students with street style punches and they were doing the wing chun.

After a while your inner forearms would get hammered and your hands would start twitching i thought this might be nerve damage so i started wearing the pads every time i was the bad guy attacking the wing chun guy.

I also heard that our Sifu in the past had made guys have to run off to the bathroom and vomit when he has demonstrated a chit sau deflection on their arm (think attacker doing uppercut punch to stomach, wing chun guy intercepts at wrist with blade of hand and forearm going forward and slightly down).

My question is could i have been doing damage by not wearing pads and what vital points are on the inside of the arm that could make you want to hurl your guts out.

Well, I don't know about the vital points, but I think I know the 'point' you're talking about... There are quite some places on the inner fore arm where nerves can easily be stimulated, and this causes twitches and it might feel as though you've got an electric shock. This is 'normal' when a nerve is overstimulated (which happens when you hit that spot) - that's the whole point of hitting there, because an opponent won't be able to (properly) use his arm for a (short) while.

(I'm not a doctor, so if you're really worried, you ought to visit one...)

However, if your arm doesn't start twitching without being stimulated (outside training), I don't think you should worry... If you can still properly use it, if it doesn't hurt at all, there's no damage - I think. But if you think it's damaged, you ought to see a doctor.