Hi, I had gone through your question and understand your concerns. I must admit that this is pretty strange symptom if this happens so quickly and I am sot sure if you describe it well. It may be allergic reaction if there is contact with some materials as a trigger. Also, it may be abscess if this is red, painful and there is pus secretion from it. Last it may be vessel anomaly and this would be pulsating lump lump in this case. I recommend to do ultrasound when it appear and then needle biopsy can be taken. Treatment depends on cause. Hope this answers your question. If you have additional questions or follow up questions then please do not hesitate in writing to us. I will be happy to answer your questions. Wishing you good health.