Tennis elbow is caused due to local inflammation near the muscle origin on outer aspect of elbow..
Next Steps
You can start with Ice fomentation, take analgesic with anti inflammatory medicine, apply crepe bandage or tennis elbow brace for support, apply analgesic ointment locally for pain relief. You should avoid any heavy work with that hand like weight lifting, washing clothes or utensils etc. If pain dosen't subside, you may start with physiotherapy for reducing the inflammation..