What would be a few reason as to why i have been so tired mentally and physically and irritable the past few days ?

See below: Stress, lack of sleep, poor diet are some. If this persists, see your physician.

See below: Winter & holiday times are very stressful. Lack of sunlight can lead to seasonal affective disorder (somewhat like depression; treated with phototherapy). Depression is common during the holidays: can present as tiredness &/or irritability. If not resolved after the holiday season, see pcp for counselling & possibly short course of antidepressant.

Need more info: There are far too many possibilities to outline without more information. Could be as simple as a common viral illness, sleep deprivation, depression, perimenstrual discomfort, a bacterial infection, work or home stress, allergies, etc. Try looking for something that changed before you started the symptoms.