Baby vomiting continuously. Advice!

My baby has lose stools once a day he is 5 months 3 days old he is completely on breastmilk . I visited pediatric one week ago he suggested econorm sachet one whole sachet morning and one who sachet evening . I mixed in breastmilk and gave the sachet . He woke up after 3 hours and I gave him milk and immediately after sometime he started coughing and vomited with force like white cuddled milk . And later he vomited forcefully 5 times removing yellow sticky liquid . He has little cold doctor suggested to put nasal drops . I'm worried about him vomiting continuously. One week back my father law was eating gutka(tobacco) and accidentally he spit it on my baby on hands and shirt is that a problem . He spitted milk the same day and in evening he spit more milk . Is that a problem I'm unable to understand what is the reason can u please advice