Hi I am Dr Fahim and I will you with you problem I have gone through your question. It appears to be collection of blood beneath the skin or muscle strain because of excessive workouts as your body building competition is ahead. Need answers to the following question to make things clear for me _ When and how did you notice this lump? _ Any history of direct trauma? _ Mobility of lump, is it adherent to underlying skin and weather skin moves over it. _ If you contract your forearm muscles, whether it gets prominent. Answer to these questions will help in your diagnosis. Anyhow to me it appears to muscle sprain. Its treatment includes rest, elevation of the limb, icing, taking pain killer medication like ibuprofen, paracetamol and local analgesic cream applications. work outs are not recommended till pain and swelling is there. I hope this will help you. Wishing you rapid recovery. Do rate my answer, if you like it. Regards