What you're complaining of could be freckles which gets exacerbated by sun exposure during the summer and might be decreasing in winter when the sun is not that strong. Without examination of the skin condition and knowing the extent of involvement.. along with this more information on ongoing medication or previous history of skin illness it is not possible to comment on the treatment that would suit you best. Please get the problem checked thoroughly by visiting a qualified dermatologist or you can visit my clinic which ever is more convenient for you. Hope this is helpful.