So I had a similar problem. Went to bed, no low space warning, woke up, low space warning. So, I went to clear caches using QuickApp Clean Cache. Well, all my caches were at 0. Which is pretty impossible, seeing as I had been using maps a lot recently, and hadn't cleaned out any caches in at least a week. So I deleted some apps and got the warning to go away. However, my memory slowly but surely was eaten away. Low space warning came back, and no matter how many apps I deleted, would not go away. Eventually, memory became so low, my phone started to shut down processes like sms/mms. Then it went into a tailspin. Actual android processes were being forced to close, and the phone became completely unusable. Soon, after a battery pull, the phone would cycle through splash screens without ever starting. Had to bring it in to Verizon so they could get in and do a factory reset, because I couldn't get to it.