Red swelling after a lipoma removal after 10 days and two drainages of seroma. What should I do? Can I play tennis? (Photo)

Thank you for sharing your question and photograph and I am sorry to hear of your recovery difficulties.  I would maintain close contact with your surgeon so that they can continue to address any fluid collections that develop.  Aspiration is the best way to complete recovery, but does result in some discomfort.  I would allow your body to fully heal before playing tennis.  Hope this helps.

When a seroma does not resolve with aspiration, and gets infected, a drain needs to be inserted and the infection treated with antibiotics as a general principle. Also, if the seroma has become an abscess, it should be opened, drained and left open while the infection is treated.You should follow up with your plastic surgeon to see if this is what is going on in your case, and keep following up closely until the problem is resolved.  Until then playing tennis or other strenuous activity might make things worse

Seromas can be an annoying complication following surgical procedures.  They occur more often following procedures on fatty tissues (i.e. liposuction, tummy tucks, removal of lipomas, breast surgery).
To reduce seromas, high risk procedures utilize postoperative drains, compression dressings, and/or "quilting" or "3-point" sutures to close and compress the cavities created by those procedures.  When seromas do develop, first-line treatment is often drainage by needle aspiration and compression.  Sometimes aspiration needs to be repeated multiple times, but hopefully there is a trend towards less and less fluid.
In the rare case that a seroma doesn't resolve, there are some alternative options.  In our practice, during the first 1-3 weeks we will sometimes drain the seroma cavity and inject a medicine called Doxycline into the cavity.  This can be a little painful because it agitates the seroma cavity, but hopefully helps it seal off.  We will sometimes repeat this injection.  
When these steps fail to resolve the seroma, we consider surgical options.  As the seroma matures, it develops a sac or wall.  Surgical treatment removes this sac/wall just like we would remove a cyst.  Quilting or 3-point sutures are used to close and collapse the cavity and a good pressure dressing is applied to prevent recurrence.