i think melasma
is related to the estrogen
content of the pills.So i think you can take mini pills or depot medroxyprogesterone
injections,but you need to stick to proper schedule. Another very safe option is a copper-T IUD, if you are happy with it. I think the latter is the best option for you if you have a child.Barrier method like condoms can also be used if both of you like it and use it regularly.
so all the best .take care.