hey... your eyes are getting strained... u feel better after stopping your works tels that.
adjust your sitting position properly so that your eyes n d monitor are at same level.sit wit your back straight. apply a screen gaurd on ur pc. check with an eye specialist if you have refractive error
. if u do have...u will need to wear glasses regularly.n if u dont ...take this measures n put refresh tears or eye mist eye drops 4-6 times /day. u can ues them evn if u apply specs.
give rest to ur eyes in between...take breaks