My father was diagnosed with collections of fluid under the skin. Should I be worried for him?

Speak with M.D. Depends on the cause of fluid collection (edema). Need to speak to the doctor to find out what the cause is. Need more info to answer this question.
Blisters?Age? It this swelling or blisters filled with clear fluid? If these are blisters filled with clear fluid this may be bulbous pemphigoid which is treatable with oral medications such as prednisone, tetracycline plus niacinamide, or low dose methotrexate. A biopsy for immunoflourescence would confirm diagnosis.