Dont feel i fit in at my job anymore anyone else feel like this?

been at my job 3years i should to get on with a lot of people now we have had a big change over of staff for the last year i dont fit in with them even the old ones are not the same towards me,its such a horrible atmosphere there now ,with the ols staff we used to have a laugh they even moan about the job the new ones and old now seem such suckups to the job and jobs woth you got there now.i have a medical problem so some things i cant do is it because of this why they are like this.anyone else feel like this at work.thankyou for answers.