Since last three times, over a period of 7 months,...

is it ok for the babies to have nausea and vomiting during cold or flu ?
its perfectly normal for such thing to happen and there is nothing to worry about
what are the treatments available for nausea and vomiting ?
there are some treatments that can relief the nausea off the baby in this age such as antihistamin drugs like citrizine in a syrup form 
why nausea and vomiting happens that often in my baby during a common cold ?
in the case of common cold you should know that its a viral infection that can turn in to a flu ( which is also a viral illness but the difference between the two of them is linguistically that flu is more agrresive in terms of symptoms and each common cold can turn into a flu ( its the same thing but if you have a stronger symptoms then its a flu ) and every viral illness in the upper respiratory tract ( i mean by it the nose tonsills brochus ears and trought )  can cause vomiting because of the affection of the infection uopn the ears or because of the body way to fight infection forces the baby to reject food whatsoever ( it happens in all of us ) so the infection will benefit from the food and strength itself so its just our body defensive mechanism against every living forign object to our body system ( e.g. viruses bacteria and fungus )
what is the possible diagnostic mesures to check if the baby is in good health ?
the medical examination and history are important to make sure that everything is ok then the doctor might ask for some basic tests such as urine stool and chest x ray if there is any infection and he might ask for blood test to check for any raise in white blood cells which indicates an infection or any change in hemoglobin values in case of suspected anemia 
what is the advice ?
we advice you to visit the pediatrician for the right diagnosis and the correct treatment