I just turned 60, and that combined with an unavoidably idle winter (weather, job and family things kept me off the bike almost completely for three months) have really taken a toll. It's a LOT harder to get back to even mediocre riding condition than it used to be. About all you can do about it, though, is not let yourself get OUT of shape, so you don't have so much work to get IN.
As for your specific symptoms, that could be almost anything. This time of year, though, it might be worth thinking about an allergy. Around here we had the wettest winter in 85 years, and the rush of new growth in spring has brought out huge amounts of pollen. People who've never been allergic to anything are sniffling and snuffling.