Okay, so I figured out that if I just converted all of the files to PNGs I was able to upload them without a problem.
My originals were PNGs but when I used a different program to resize them quickly, it converted them to JPEGs. 
So from now on: I will just stick with PNGs. Hopefully that will remedy the situation.

Also, I did a speedpaint today! So that has just been added. I haven't gotten to do much extra painting since I started on everything for the convention and it was nice to just sit here and paint at random.