Yes, anxiety has a lot to do with IBS symptoms due to the mind, gut link, which produces chemicals such as serotonnin and gastrin that makes symptoms worse.
Diarrhea can also make you feel very weak, as you do become dehydrated and also lose electrolytes, such as sodium, calcium and magnesium.
Do make sure that you drink plenty of fluid and try to eat a good diet with plenty of fruit and veg. You may benefit from taking some Metamucil which is a water soluble fiber supplement. This can help to bulk you up and thus stop the diarrhea.
Have you seen your doc at all for investigations? If not, then I would consider going along so that he can take bloods and examine your belly to ascertain what is going on. If nothing is found, then I would suggest that you try doing some deep breathing exercises such as Qi Gong breathing exercises to reduce your anxiety levels. I would also suggest that you have some acupuncture treatment, as this is very good for helping stomach problems and anxiety problems. If you don't like needles, then there is always Japanese style which is very gentle, but very effective. The needles don't hurt though.
Anyway, hope this helps and good luck?