You don't list your hair properties, which would help everyone a lot in advising you. Here's a link to help with that: Live Curly Live Free - Home
Nexxus Mousse isn't discussed here a lot. You didn't list the ingredients or the other products you use, so it's had to help. These are the ingredients that I found for Nexxus Mousse Plus, when I did a search:
Water (Aqua, Eau), Isobutane, Hydrofluorocarbon 152A, VP/VA Copolymer, Polyquaternium-11, Propane, Polysorbate 20, PVP, Polyquaternium-4, Fragrance (Parfum), PPG-12-PEG-50 Lanolin, Olealkonium Chloride, Polyquaternium-7, PPG-9 Diethylmonium Chloride, Sodium Benzoate, Linalool, Propylene Glycol, Cyclopentasiloxane, Hexyl Cinnamal, Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde, Cyclohexasiloxane, Sorbitol, Glycerin, Butylphenyl Methylpropional, Benzyl Salicylate, Cocamidopropyl Betaine, Limonene, Gelatin/Keratin Amino Acids/Lysine Hydroxypropyltrimonium Chloride, Hydroxycitronellal, Hydrolyzed Elastin, Eugenol, Benzyl Benzoate, Benzyl Cinnamate, Polyglyceryl-3 Distearate, Polysorbate 60, Stearic Acid, Palmitic Acid, Myristic Acid, Guar Hydroxypropyltrimonium Chloride, Triticum Vulgare (Wheat) Flour Lipids, Persea Gratissima (Avocado) Oil, Tetrahexyldecyl Ascorbate, Glycine Soja (Soybean) Sterols, Alpha-Glucan Oligosaccharide, Ceramide 3, Ethylhexyl Methoxycinnamate, Butyl Methoxydibenzoylmethane, Tocopheryl Acetate
They have some others, I think. If you're using products like this, the propellant is drying, the 'cones can coat your hair and cause build up if you're not removing it (which prevents moisture from getting in)--and lots of other issues.
Without more information about your hair and products--it's really hard to advise you. My first thoughts would be protein followed by moisture.