Hey guys! I need some help! When i do my drawings they're a big sized file with a resolution of 200 to 300 as a PNG. But for some reason, when i submit it here, i get this weird blotchyness!>.< On deviantart art and tumblr, it looks fine. But here it looks like it has really bad quality and i don't want that!

So please, if someone can help me fix this problem, i would really appreciate it!!TTwTT