Welding Tips and Tricks

Hello i am very new to welding and i took my very first class on it today in fact. I had fun with it but i am slighly worried about something. I was learning how to do Mig, Tig, and stick welding in about an 1 hr and 30 mins with 30 min time slots for each roughly. The very first time i watched the instructor demonstrate the weld my eyes hurt a little when i first watched
(i was wearing a "proper" helmet for welding). They didnt really hurt to badly and i didnt get blurry vision or started seeing spots like he said we could so i figured it was just because it was the first time i saw someone weld. After the class everything was fine for the next couple hours and then long about 7 pm i had a very minor headache and again i thought it was fine because i hadnt drank much during the day. At 9 pm though i had a pretty bad headache so i was slighly worried it might have had something to do with the welding. I know i might be overreacting but again today was the very first time i ever welded and it was for a straight 1 hr 30 mins. I was in a very good building that had ventilation shafts in every booth and we never worked with any pieces of painted or galvanized steel so it was as far as i know safe. I want to trust the instructor with him saying that using the #9 setting on the helmet should be fine but i just wanted to ask some other people who might have more experience than him. The headache is not as bad now but still i wanted to be sure that there isnt anything i need to worry about. Thanks

Your helmet setting depends on the amperage of the weld. For most everything we do I leave my helmets on 11 or 12.

i typically use 10 for most stuff.
its not just amperage but also what material. anything shiny usually go up one setting.