The autoimmune connective tissue diseases are usually treated with the same sorts of medicines. It sounds as if you might have the sort of symptoms that's often called Undifferentiated Connective Tissue Disease, UCTD. That means there are no specific signs of any particular one. In the case of lupus there are only 4 specific signs. Many people who have a lupus diagnose could well have got an UCTD diagnosis from another doctor. There is not necessarily any difference, it all depends on how the person is affected and how badly.
There is no telling at time of diagnosis how any of the diseases will develop. Many cases never get worse and many are effectively treated with medication. Plaquenil is a very important disease modifying medication that can reduce overall disease activity which takes several months to fully kick in. People often need help with symptoms in addition to whatever disease modifying medicines are needed.
Fish oil is supposed to help reduce inflammation. It's a source of omega 3 fatty acids and there are others. Cutting out refined sugar, animal fats and junk food will help too. Some people react badly to certain food items, but it is very individual.
Many people with lupus like disease are DHEA deficient so supplements are helpful. DHEA might help with general wellbeing but it can have some unwelcome side effects - deepening voice, facial hair, skin eruptions, and mood swings. It must be obtained from a reliable supplier which is often a compounding pharmacy. Health food shop supplies are often not reliable.