#1
Now this might sound like a weird question, but I cant help but wonder. Im sure that my lack of being able write stuff is from not knowing how to apply theory, but whenever I go to make something, usually my mind just gets hijacked by some song I heard that day or something. Does anyone have this issue? When people go to write a song, do they hear that song before they ever pick up the guitar and play around?
#3
Yep. I've spent ages in the past trying to improvise, and all that came out was the wombles

I got round it then by going back to basics, and limiting myself to choosing 4 or 5 notes to use - so I physically couldn't play the wombles with them, then and came up with a rhythm, and a lick from that rhythm/those notes, then expanded on that til I was womble free.

Don't worry - its incredibly frustrating but also totally normal. Plus, if you can play a song you've got stuck in your head at least you can play by ear, so you'll be able to play your own stuff when you hear it in you're head.