Welcome to the forum! Your symptoms do not suggest of Fibromyalgia. The characteristic difference between Fibromyalgia and other joint disorder is that Fibromyalgia presents with muscle pain. Unlike arthritis, the incapacitating pain is not in the joints but in the muscles and ligaments. Fibromyalgia is known for presentation of pain at specific sites known as tender points or tender spots. The pain is commonly located in the neck, shoulders, back, and hip and the tender points are located in the same regions. The tenderness is worse in the mornings and has been described as flu-.like, burning, throbbing, aching, or stabbing.
Since you have no muscle pain, Fibromyalgia can be ruled out straight away.
Positive ANA suggests an autoimmune disease.The most probable causes suggested by your symptoms of Joint pains, Pleurisy, Stomach problems and positive ANA could be SLE( Systemic lupus erythematosus) or Rheumatoid arthritis(RA).
SLE presents with the same symptoms as Rheumatoid arthritis but the joints of neck and spine are not affected in SLE but they are affected in RA.
As you have pain in the spine along with other joints, the most probable diagnosis of your symptoms could be Rheumatoid arthritis. The diagnosis of RA can be confirmed after the following investigations-Anti CCP antibodies, Complete blood count, ESR, C-reactive protein, X rays and MRI of the joints. Please go for all these investigations to rule out the disease. Hope this helps you. Take care and regards!