Hi Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern...
Yes
Ibuprofen is safe for groin pain to child, unless the child is allergic to it. Actually ibuprofen is one of safest painkiller that could be given to a child.
You could also give him ibuprofen &
paracetamol combination to be more effective.
Most common cause of groin pain is
injury to muscle of ligament. Pulled muscles, ligaments, or tendons in the leg may cause symptoms in the groin. It is important to look for other causes of groin pain when you have not had an injury. In absence of any injury, this condition amy be cause by infection of testis, inguinal
hernia etc.
I would also you to consult a pediatric doctor(child specialist), as the groin pain & red spots on chest might be linked and have developed as a result of a systemic infection.
Hope this information helps