Please help a sad fish

Question
Hello.   
My name is Rusty and I'm poorly. For some time now I have had problems maintaining my bouyancy. This often results in me exerting huge levels of effort to swim downwards before quickly floating back to the surface of my tank. This is not always the case as sometimes I can swim quite content with not a care in the world, however at other times I can become quite distressed and assume a state of depression floating at the water's surface. Recently I have also been excrementing air bubbles in my faeces which is also quite disturbing. Please help me if you can!   

from Rusty the not so happy goldfish x

Answer
Chances are you have a bladder condition or an internal parasite. This sometimes can be treated and sometimes not, depending on what exactly you have. I would recommend getting a medicine which covers internal parasites. Also, try eating some romaine lettuce, this can often be a good addition to your diet and can sometimes relieve bladder issues. When you use the treatment be sure to follow the directions exactly even the water changes needed. Hopefully the treatment will be able to help you. I hope I have helped some. Let me know if you need more help.