Cold and cough will not harm your baby directly but its troublesome for you, for fever you can consult Doctor and have paracetamol its safe, for cough you can;
*Dry ginger helps little. A small pinch of dry ginger powder with some jaggery, boil well and drink like tea.
*Green tulsi tea also helps.
*You can keep a small cinnamon in mouth, its safe and works well in cough.
*Biting clove is also useful.
*Honey lemon and ginger tea also is good and as long as your diet is concerned, since its second trimester, start day with apples/coconut water/ soaked almonds etc. Have iron, magnesium, folic acid rich diet which should in your daily food consisting vegetables, fruits, nuts, seeds, chicken, fish, mutton, eggs everything all regular food no need to start anything special..Also include milk, cheez, paneer to ur diet becz calcium is required now..
U can have one cup of coffee or black tea a day . Nd as much of fennel ,chamomile, fruit , caffeine less tea.
Take ample rest and drink lots nd lots of water. U can go fr walks if u want nd only if ur gynae permits.
Hope you find this helpful..