Hello, You have been bitten by some insect/bug in the beach after which you have developed a sore spot that is red and throbbing. It is common to develop swelling and redness around the bitten area when you are in the beach. Some beach bugs are sand fleas, beach spiders, etc. Wash the affected area thoroughly with clean running water and medicated soap, you can apply ointment Soframycin on it for relief. Take acetaminophen, one stat when required to reduce discomfort, pain and inflammation. You can take antihistamine, one stat at bed time to reduce the symptoms of allergy. You are suggested to refrain from touching, picking or scratching the area affected as it may aggravate the condition and may cause an infection. In case of itching, do not scratch. Apply ointment hydrocortisone on the affected part. Aloe vera gel also gives relief. In case, symptoms of fever, headache, and muscle aches manifest. Get clinically examined in the ER, get done required tests and investigations, you may need urgent medical care and treatment. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician