A viral cold or allergy is most likely the cause of your symptoms. Saline nasal drops or saline spray are generally harmless and can help moisturise and clear the nose if you have a blocked nose and have trouble sleeping. Warm liquids, sleeping with the head slightly raised, and inhaling steam before bed may all be beneficial. If it works for you, paracetamol can relieve bodily aches, headaches, and sore throats. Strong nasal decongestant drops can exacerbate blockage later, so avoid using them repeatedly for several days without consulting a doctor. See a doctor if you experience a high temperature, difficulty breathing, a strong headache, chest pain, or symptoms that last for longer than a week.