Older guinea pigs, medication

Question
We have two guinea pigs Theodore and Roosevelt(both males).  They are a little over 4 years old, and have been living together in a 2X4 foot plastic walled home, on pine chips, since they were young.  Theodore is an Absynnian, and Roosevelt is an English.  Theodore has had restricted mobility of his hind legs for about 6 months, and is currently receiving rimadyl(1/8 of a tab-25mg) every other day.  It seems to help him tremendously. The vet had never prescribed rimadyl for a cavy, and was concerned that it might cause a problem.  There have been no side effects that we can notice.  He also has "weepy" eyes, and I clean the crust from around them every other day with a wet tissue(it's hard to believe they can complain so loudly).  Do you have any advice for treating his conditions?  

Answer
Hi,
  What you can do is try switching to another medication or Just keep on doing what you are doing.There isn't really much I can tell you because I'm not a vet but I wish I could give you more advice. Thanks for the question and I hope this gets better.
                                                       Blair