I have really bad gas i think is due to my lack of good bacteria. i took probiotics already it don't seem to get better. i also feel weakness in knees?

Gas pains: Your symptoms are fairly common and could suggest many underlying conditions or none at all. Do you eat a lot of gas-producing foods, e.g. beans, broccoli, cauliflower, cabbage? If so, you might try cutting these out and see how things go. You may be significantly lactose intolerant or have gluten sensitivity. I suggest you see your physician for evaluation.