53yr old father injured thumb at work 3m ago took antibiotics for one week. is now experiencing numbness from the thumb to the forearm. checkup?

Yes: You need to have the arm evaluated for nerve damage or compression.

Yes, this should: Be medically evaluated. For signs of infection (in spite of antibiotics) he should be seen urgently.

Yes: He needs to be evaluated by a neurologist. Best wishes.

Worker's comp: Antibiotics are only necessary if injury lead to or could lead to infection. Numbness 3 months later may or may not be related to original injury. However, in the states, all work related injuries must be reported to worker's compensation if you want work to take care of injury. Once an outside doc starts caring for work injury, i believe that wc is no longer available. Check w/your attorney.

Yes , see your doc: Get it checked , for any pressure is being built up in side your hand compartment (s) , or infection setting in the hand.

Numbness: Your father may have injured the nerves to his thumb. Consult a hand surgeon for help.

Arm numbness: It is unusual to see a retrograde paresthesia from a distal injury unless there are signs of reflex sympathetic dystrophy or an ascending infection. I think examination by a hand surgeon would be in order to determine the actual cause of the numbness.

? Carpal tunnel syn: Our thumbs provide 40% of the functionality of the hand hence it is the most important digit in the hand. Best to see a hand surgeon asap, to rule out issues like an infection but this may likely be a carpal tunnel syndrome presentation. In either case, s/he will be able to give you a clinical diagnosis and manage you accordingly.