hello, welcome to HCM,
as per the details u have given,
i am sorting out the most possible causes of painful red eye...
1.computer vision syndrome
due to your software job , as becoz constatnt watching of computer screen leading to dry , irritating red eyes..
2.refractory errors ..i.e eye sight..so check out the eye power
, whether it has changed , by cosulting a ophthalmologist..
....most imporatant thing to rule out..by measuring intra occular pressure...by an ophthalmologist
4.some times allergic conditions also causes..
so, red ,painful eyes to be properly evaluated and you will be treated accordingly..
hope this will be helpful for you...so immediately consult a ophthalmologist