(shudders. The face of true evil. Zuckerberg XD)
Got just a bit more advice, if this doesn't apply, feel free to ignore.
Keep creativity on your terms.
When you feel boxed in or stuck, break the rut by switching tactics. I've had to do this many times, especially while drawing panels. When I get frustrated by something, I have to really fight the urge to not focus on it. (Believe it or not, I actually lose this battle more often than win it)
Many times I've simply moved on to a different panel, and then the previous one makes sense, allowing me to tackle it again.
Also, when I draw big pages, it can be really daunting. And if I haven't gotten through it after a few tries, then I change tactics and draw the big page...inside a tiny panel. Doing this focuses my angles and perspectives into a tighter format, which really helps me out.
I know that advice is about drawing, but it also applies to storytelling as well. Like I said above, keep it on your terms, don't let your creations tell you what to do. Wrassle that control right back.