Paranoia and fear about pregnancy. Mind?

Hello doctor. Me and my girlfriend had a totally safe encounter on 31 January 2019. We used a condom and there was absolutely no penetration ever. I consulted gynaecologists on practo and everyone said no chance of pregnancy. She expected her period on 4 January but it was late by 2 weeks but finally came on 17 January. It was a normal period and hence pregnancy is totally out of question and I have also consulted gynaecologists about it. She has now fallen I'll with severe viral infection and vomiting and diarrhoea for which her doctor has given her antibiotics. Even after all this, the delayed period has put a lot of stress on me and I am unable to get rid of the paranoia. My concerns are totally unnecessary still I'm not able to get it out of my mind. I have lot of important work to concentrate on but I'm unable to do it. What should I do to get rid of my paranoia and have a healthy state of mind?