It sounds like you have a number of potentially complex medical problems, and you are asking several questions here, but I will try to make some general observations.
First of all, I would definitely suggest that you keep up a good working relationship with your
internist, because it sounds like they are doing their best to diagnose and treat your various medical problems. With such a complex medical history, your
primary care doctor will be your best ally in helping you to live a healthy and comfortable life.
With respect to the lovastatin, your internist put you on that presumably because of your very high cholesterol levels. This medication should lower your cholesterol, which is an important step to prevent heart disease down the road. Occasionally, medications like lovastatin can cause muscle pain or swelling. They should not cause
arthritis, however sometimes muscle pain can be confused for arthritis, so I would definitely talk to your doctor about this to make sure you are not having an adverse reaction to the lovastatin.
With respect to your red blood cells (corpuscles). There are numerous conditions that can make them larger than normal, most often vitamin deficiencies or alcohol consumption, but also several other chronic medical diseases. Talk to your internist about this problem as well!