browning, have a few possibilities, please help.

ok, so my plants seem to have little brown spots all over the leaves, especially around the connection point of the 5 leaves. they are shrivling up as well. my humitidy stays 29%. my temperature is 75*-85* daytime and 69*-73* at night time. my thermometer says the lowest the temp has got was 67*. the highest was 83*. this was based on a week long period. i cant tell what my problem is. im using a 250w hps bulb sitting 3 ftt above my plants. i had switched to a 400w sitting at the same height a few days ago because the temperature was getting too low. do you think that maybe the sudden increase in temperture caused this?

wow that is a major problem
I would say burnt by the lights

what should i do?

is this your only plant? if its not I would just kill it if it is move your light up to 24 inches or so and nurse it back to heath

definitely under watering man.....check the last page of my journal if u wanna see what 12-36 hrs of no watering did to mine.

https://www.rollitup.org/grow-journals/120219-side-side-stealth-closet-grow.html

*Possibly bulb too close, but i doubt it.

probably is burnt...give it more air..i was growing in a closet and it did that shit so i made a grow box that gets plenty of air and it hasn't done it since..it actually is growing really well now

That does not look like a heat problem at all. Check out the pics here under ferterlizer burn. So aside from the all the info you gave on light and heat; what have you been feeding them? What soil are you using? How often do you feed? and Are you in flower or veg?
Ganja Guerrilla's Hall of Marijuana Plant Abuse

Brasmith is right... that looks like some serious nute burn. What nutes are you using? At what strength and frequency? At this point that plant is pretty much trashed and should probably be put out of its misery. Live and learn my friend, live and learn....