A fever around 101.9 with headache behind the eyes that returns after Dolo can be due to a viral infection like dengue, which can cause body aches and eye discomfort. Take proper rest, drink plenty of fluids, eat light food, and continue to control your fever as advised while monitoring your temperature regularly. Avoid self taking multiple medicines, watch for signs like severe body pain, rash, or weakness, and keep yourself well hydrated. If fever keeps returning, lasts more than a couple of days, or new symptoms appear, consult a doctor for proper tests and care.