Hi mum, I went through something similar with my child also, especially those morning sneezing and runny nose when exposed to air-con. If doctor already diagnosed allergic rhinitis and the nasal spray helps, it usually means the inflammation is controlled only when medication is used, so stopping it will make symptoms come back quite easily. At home, what helped me a bit was reducing triggers like regular washing of bedsheets in hot water, using dust mite covers, and keeping the room temperature not too cold. For long term, I would honestly rely more on follow up with PD or ENT rather than herbal remedies, because allergies in kids tend to be more about control than cure, and the doctor can adjust treatment if needed.