My short term memory has also been affected, particularily lately. I have been trying to do a few things to improve my memory, here are some suggestions:
-don't drink alcohol or take drugs unless prescribed
-a lot of exercise (this really helps with memory actually, I did a study in Biopsychology relating to how we can actually "replace" brain cells in our hippocampus, the memory center of the brain, via exercise).
-lower stress (anxiety and stress gives us major adrenaline boosts, and there isn't much else left in our brains other than our 'fight or flight' modes to recall much. Also, we are quite often more likely to dissociate during stressful times than any other time) -- to keep stress a lot lower I'm learning meditation and deep breathing techniques, it's helping a lot.
-omega-3s (fish oils really help our memories), green teas, and a low sat. fat diet.
-challenge/stimulate the brain-- I do sudoku, a lot of reading, crosswords etc.

I've found that the omegas have helped me a lot , although my memory isn't as up to par as I'd like it yet.