Brief Answer:
Read below.

Detailed Answer:
I read your question carefully and I am sorry about the persistent symptoms you are experiencing.

It sounds like a case of allergic rhinitis, inflammation of the nasal cavity. Due to the congestion it could get complicated with infections like sinusitis which could cause your headache.

As an initial step I think you have done the right thing by taking Claritin D, which contains an antihistaminic like loratadine to counter allergic reaction and a nasal decongestant like pseudoephedrine. The loratadine contained in Claritin D could cause some sedation as a side effect though, which might influence your difficulty staying awake.
A corticosteroid like the nasacort which you mention is also used to fight inflammation. At times oral corticosteroids can be used instead of spray, but I would be reluctant about that due to possible side effects especially in the elderly.

For the headache you can add to your treatment an anti-inflammatory pain killer like Ibuprofen.

If the symptoms persist for several days or if you develop fever, greenish nasal discharge then the possibility of needing antibiotics for a sinus infection must be considered after being examined by your physician.

I hope to have been of help.

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