update:
my mobile carrier, us cellular, only has one suspicion as to what could be causing this problem. After I use a certain amount of mobile data, my connection speed slows down a bit, and when it does the subsequent connection is said to be "throttled". So their guess is that this phenomenon is causing the session timeout to happen, although I'm not convinced. I've been on plenty of slow internet connections via ISPs over the years and I've never experienced this timeout thing happening.
But through a speed test conducted by google, after a google search for "speed test", it shows my current download speed at .12 mbps and upload speed of .73 mpbs. That is insanely slow, but none the less I can still access webpages with little trouble and even stream videos online with limited buffering.
So I guess I'm stuck dealing with it, since there are no other ideas.