Chickenpox was very inconvenient for my brother at 32 (and pre kids - did not have friends with kids). He got a doozy of a dose and had it through his hair, around his privates etc. Complication was the fact that he had gone to NY on business and all of a sudden could not fly for 3wks. He had to stay in his hotel room. Even his friends in NY could not come and visit as (after they all called their mum's) they discovered they had never had it too.
Only a blood test can tell you whether you have had chicken pox or not. Before we had a family l went for a blood test to see whether l had had chicken pox as a child, thinking l hadn't and mum saying l hadn't. But according to the blood test l have had it. Sometimes you just get the cold symptoms and don't need the spots...
And if you have had chicken pox then you are more likely to get shingles (esp if immune system is down). Poor mum had shingles when she was haivng treatemnt for cancer... and she had no hair and shingles all over her head. And yep she had had chicken pox as a kid... She would rather then shingles as its very very painful. Come to think of it my sil had rash on her arm last year and her arm was very sore ened up being shingles