The bumpy spots which you have mentioned could be an allergic reaction
to some newly introduced food item.
Also the skin lesions may arise due to any exposure to an outdoor allergen. Correct observation of his playing activities and exposure to the environment can help in identifying the cause.
As these are non itchy and non progressive, these should settle down.
However it would be best if you can provide some photos of the skin bumps.
If you feel the condition is worsening kindly consult your Skin Specialist.
Wishing your child a speedy recovery.