I'd guess that you're getting ahead of yourself. I've mentioned in other parts of this board that I used to be a pretty serious player in the day but put it down for a while. Recently picked it back up but don't have the practice time now I did 'in the day'. Like a bike, I still know all the licks but my hands aren't back up to speed. I notice that when I get rippin' a little now that it is not with the same physical confidence I had when I committed time every day and did so for years.
My thought is that you've built up some skill after 6 months and that is a great thing. However, you fingers work both on actual strength and also muscle memory and it sounds like you are pushing just outside those boundaries.
Especially when you are improvising, you might understand where you want to go intuitively but that muscle memory and the brain/hand connection is still forming. That take time to connect.
In addition to knowing scales and how they work with chords etc, if you're playing bluesy stuff (since you'd said you've been focusing on pentatonic), know the blues scale variation and also start digiing in to the blues lick vocabulary. With most rock playing, it has been built on a vocabularly of licks. Like talking, if there weren't certain patterns formed, you would talk gibberish. I would poke around some of the blues lessons on this site to pick some up. Improvising is so much of making it up as you go but being able to string together learned elements of playing from the various styles' licks in to something that becomes uniquely your own from that vocabulary.
My thoughts (from a rusty old player).
