If i am pregnant when should i stop taking my medication?

i think that i may be pregnant but ony the stage were the eggs are lining the uterus,but i take medication which is co-dydromol 10/500 and diclofenic 50mg for arthiritus and zopiclone 7.5mg which is for insomnia.i supposed to take the arthiritus tablets 4 times a day but im worried about taking them so im only taking when im in really bad pain which is proberbly once a day i do need them more than that but as i say im really worried about taking them just in case it does any harm if i am pregnant can someone advise me what to do thanks kerry x