p0psicle

I've recently discovered my blood type is B+, but both my mother and my father have blood type O. I double checked it so I'm sure it's B. My parents did their blood types when they got married (at least). However, it's impossible for me to have B type when my parents both have O, because I must have gotten the B from one of them. So I'm worried that my father might not be my father. I look completely like my mother and there is no obvious resemblance with my father, apart from a wider nose tip and maybe the way my feet look. I know my mother used to fool around back in the day (yes, around the time I was conceived) with her ex-husband, which DOES have the B type blood. I don't really look like him either, except my rather hairy arms, which both my mother and my (known) father don't have (and it's a dominant trait as far as I know). I'm unsure of what to believe! I've even considered being sick and my blood type changing because of cancer or God knows what... but that's still an unlikely scenario. Besides, I don't know if it changed because this is the first time I've tested for my blood type. My mother always assured me that I must have O blood type because both her and dad have O. My mom always seemed to be very sure my father was my father. I have my known father's wider nose tip (my mom has a thin nose) - but the blood type matches my mother's ex husband (which also has a thinner nose). And I also resemble my known father's mother very much. I can't do a genetic test, I can't even tell my father that I have a different blood type because I want to keep this a secret. What are the odds that my dad is not my dad? I know broad noses are dominant, so one of my parents must have had a broader nose (my dad). But also one of them must have had B blood type and hairy arms, and that's my mom's ex husband. What is the likelihood that my blood type changed from O to B because of some illness? I also attached a photo of me (right), my dad (middle) and my mother's ex (left).