Stress or something else ?

For a while now I have been feeling constantly tired and often cannot be bothered to do anything. I always want to sleep and find it difficult to get up in the morning. I also have gone from being very ambitious and self confident to having low self esteem and giving up on things that used to be important to me. I ve even started tripping over words but its not exactly a stutter. I am more irritable and snap at people which is unusual as I always used to be very in control of my emotions. Sometimes I get urges to just start crying for no reason and I get suddenly tense and anxious about small things before realising nothings wrong. My general low mood comes and goes, sometimes I forget about it for a while but then it comes back. Its sometimes worse than other times, at worst it makes me want to be by myself completely and think, cry or sleep. I think this all started to happen about September/October last year but got gradually worse. It almost went away for a couple of weeks recently but in the past week its coming back. I m not sure whether I m just stressed and making a fuss about nothing or whether this is something to worry about. It isn t constant so im half convinced i m just being silly and overreacting.