Bit of back story I promise to try and keep this short 
I work in a department with only 1 other person lets call her Lisa. She has worked with me for just over a year and we get on really well. I am 42 she is 22.
She has a history of MH and is very honest and open about it. Our employers knew this before offering her the position.
I must add it is a very supportive workplace and they were fantastic when I had a breakdown a few years ago.
Everything has been fine for around 10 months but things are happening and I dont know if its a pattern or coincidence.
I am rarely ill but last November I had a very bad chest infection. I dragged myself in on the Thursday clearly unwell and was told not to come in the following day.
Friday morning I text my boss and Lisa to say i was not coming in. Text back from Lisa "oh neither am I. I have swollen tonsils. I feel really bad"
Now the day before she seemed perfectly well. I then text back and said "well we cant both be off as nobody to run our section"
In the end I went in to work.
I was in a bad way but managed the full day.
That evening I ended up in hospital as the chest infection aggravated my asthma to the point my inhaler had no affect. I was off a week. Lisa returned to work on the Monday perfectly well.
Earlier this year I had annual leave. I was off on a Monday.
Half way through the day Lisa had to leave work to go to a & e as she could not see out if her eye.
They could not find anything wrong and the following day her eye was fine. A visit to the eye clinic 4 days later revealed nothing.
3 weeks ago I had a vomiting bug. Called in to work my poor boss had to hear me throwing up while trying to tell them I would not be in for the group training that day.
I found out that Lisa had suffered a panic attack 5 mins in to the training and had to go home.
On Friday I have to leave work early for a chest xray.
Work are fine no issues. Last night Lisa text me to say she has a MH appointment in the Friday morning so wont be in till later.
I have a weeks leave coming up and its making me anxious that Lisa will be ill or something else leaving our department without staff.
Is there a pattern or is it all in my head?
I must add Lisa tends to visit a & e regular for what appears to be minor things.