Talk to General Physician on Fat Digestion

AOA. I'm looking for an expert in digestive problems. My stools are yellow and greasy. They float in the toilet. I think I'm not digesting fats well. My skin and lips are always dry and brittle. I also have muscle weakness and joints hurt if i move them too much. I bought some digestive enzymes and took them for a month which turned stools brown and really improved my health. But they are very expensive and I can't buy them every month. Please can someone help me find the problem?