I have problems related to my already service-connected disability, can I get a disability rating for them?

Yes, you can! In fact, these types of service-related disabilities have a name: secondary service-connected disabilities. The regulation, 38 C.F.R.§ 3.310(a), provides:

[D]isability which is proximately due to or the result of a service-connected disease or injury shall be service connected. When service connection is thus established for a secondary condition, the secondary condition shall be considered a part of the original condition.

For secondary service-connected disability claims, as with all service-connected disability claims, medical nexus evidence is the key to success.   That is, a VA examiner or a private physician must find, within reasonable medical probability, that the service-connected disability is a cause of the secondary condition.   

A clear example is a case where you take pain medication for your service-connected back disability, and this medication causes an ulcer or gastrointestinal disability. Assuming a physician’s opinion supports this theory of causation, the ulcer or gastrointestinal disability would be considered a secondary service-connected disability. 

Let’s look at a less obvious example of a secondary service-connection. You have a service-connected knee disability, which causes instability during walking.   One day you walk up a flight of stairs on your back porch. Due to the knee instability, you fall and fracture some vertebras in your spine. Since the service-connected knee instability is a cause of the fall and subsequent back injury, the back injury would be considered service-connected.