My lovely cats (persian and mainly indoor) have brought fleas in and I didn't realise so they're now all over the house! I treated them with Bob Martin spot treatment 9 days ago and bathed them with flea shampoo twice. Vacuumed, charged bedding, etc - am I ok to use the spot on repellant (so different to the previous treatment) or do I need to leave it 28 days between any treatment?