Am I paranoid or...?

Am I paranoid or is actually happening, since Friday the 8th I've been getting this weird feeling that my fiancé might be cheating. I'm not sure how to put it but I was at work and I asked him to put money in the bank for me which is right down the street from our home, instead he went to one that's about 30 minutes away, I asked him why and I never got an answer, I also found a weird number in his phone that's unlike any of the ones I seen before and before I could go thru his phone it was deleted but not the others. Then this morning he texted me and asked why I love him knowing for the past 2.5 years that I love him and why I do. I feel like I'm going insane and questioning myself if he is or not. Some one please tell me I'm just paranoid and I'm just thinking this up.