hi this is dr.subhadeep.thanks for the opportunity for helping you. as per your description this fits your assumption of cellulitis though I would like to get few more informations 1) did you get your sugars checked recently. if not kindly get your sugars checked, fasting blood sugars as well as post-prandial blood sugar levels.if you have recently developed diabete then your immunity will be lower and you might get cellulitis due to streptococcal infection or klebsiella or pseudomonas infection. 2) kindly get a total count done which will guide you regarding the extent of infection and help in considering your decision to wait till your appointment.kindly enlighten me about any history of injury over the affected site. as u have told that the lump is tender,warm and non spreading it fits the diagnosis of evolving abscess secondary to cellulitis.in that case incision and drainage may be required once the abscess localises. kindly start with the following group of drugs for the time being: t. amoxicillin+clavulanic acid combination 625 mgx3 times. these will either resolve or localise the abscess,one H2 receptor blockerx2 times before food,a painkiller,t.chymotrypsin x3 times to reduce inflammation. you can get an USG of the affected site to be sure of diagnosis.all the above mentioned medications are to be taken for 5 days. if the abscess/cellulitis is not showing improvement in 3 days post medication with high total count,bld.sugar levels and USG proving evolving abscess then incision and drainage to be considered under spinal or local as per your pain tolerance and size of swelling kindly let me know if the consultation is beneficial. regards