How can i put on healthy weight?!

How can i put on healthy weight?

i think i have some kind of super metablosim. i'm about 6'3" or 4" and 145 lbs. i'm usually around 155 to 160 but i've been doing push ups, sit ups and dips 4 or 5 days a week for a little over a month. in doing this my body has become more toned but i guess i burned off every ounce of fat i had and now im down to almost 140.
i eat constantly, and no matter how much i eat, within the next 2-3 hours i'll be starving again. i have a very healthy and well rounded diet but because i'm so hungry all of the time i can't just eat 3 big meals a day or else i'll be ready to pass out from the hunger at certain points in the day. i need nutrition all through the day or i become cranky and tired and can't concentrate on things the way i want to.
i have a very limited budget as well so i cant afford to sign up for a gym right now or buy weights. i pretty much spend all of my money on food. i'm 25 and i've had the same body type since i was like 13. can anyone help me with this?

I think you have a thyroid problem.
Go see the doctor:this ain't good.
Some blood will be tested and if it is what I THINK:THERE IS A CURE FOR IT.
DO NOT THINK ADDING MORE FOOD WILL HELP.
SKY