That stinks. Injuries like that are a pain and not just in the literal sense. Tennis elbow is a stress injury usually from a repetitive motion and normally gets better with some minor care. It's on the outside of the elbow. Is this where you have your lump? Tennis elbow is actually a tendon issue where small tears have developed. It can turn into a chronic pain and hurts to touch it as you describe. Personally, I'd see an orthopedic doctor for confirmation that nothing more is going on (as it sounds like doctors are available to you) and definitely a physical therapist. They can help you with stretches, icing, etc. to speed recovery. Rest is essential and you can take an otc pain reliever like ibuprofen (if your doctor is okay with that). https://www.webmd.com/pain-management/tennis-elbow#1
Another reason to see an orthopedic doctor is to make sure that you don't have elbow bursitis. This is inflammation of the bursa of your elbow which is basically a fluid filled sac which we have so muscles and tendons glide easily over joints and bones. Normally bursa is flat but when it becomes inflamed, it can become a lump because it swells. Really though, if this is bursitis, the treatment is similar to tendonitis. Nsaids, rest, protect the elbow. https://www.webmd.com/arthritis/olecranon-bursitis#1
But I'd want to know exactly what the situation was myself so see a doctor willing to really dig a bit deeper to diagnose it. Let me know what they say!