since being out of hospital I can't stop crying...

I don't know whats wrong with me , last year on my birthday I was rushed in to hospital and nearly died from septicaemia and was put on life support , they had to operate on me to get pus out from round my organs , I then had to have a op 3 weeks ago due to getting 2 hernias so they had to open old scar since being out of hospital I can't stop crying I get out of the house and see people but when I'm alone I just cry . I'm happy one min and crying the next , in 4 days it's a year since I went through hell and I don't know if my problem is all in my head please help me I hate being like this