The most common causes for your symptoms are
-if associated with itching Dermatitis
For each and every disease i have mentioned you do have investigations to rule out them and in every diseases the common site of the red bumps are knuckles and toes.
In case of dermatomyositis as it is a muscle disorder you dont develop the symptoms of muscle at first but once the redbumps appear slowly the symptoms of the muscles may be seen.Treatment includes steroid
In case of gout you can rule out by checking the uricacid levels
In lichen planus there will be flat bumps present as the first symptom.
So you first need to diagnose the disease for correct treatment you better consult a dermatologistfor this.Thank you.