My eyes burn, and it's hard to figure out exactly what causes it.?

As you say a lot of changes here. Try using polarized sunglasses not transitions on the bus and for the walk. they cut down the glare a lot more and get them as dark as possible. Computer screens tend to dry the eyes. Make sure you drink lots of water - not tea and coffee which tends to make matters worse. If you are dehydrated your eyes dry as well. Adjust your computer screen properly - put details on this in many times to answers. Get a break from the screen at midday. Ease off your computer usage outside work. Look at anything in the office which may have an effect. Sitting beneath an air conditioning outlet for example is diablolical on the eyes. New office furniture can be a problem as well. Anyone wearing perfume close to you? I find perfume affects my eyes particularly in summer. After that you are searcihng for possible allergies.