wat do you do if you have  a 3month old baby who is cranky and you dont no why and i breast feed so it feel's like his teeth are coming in soonhis gum's are so hard?

My 4 month old baby recently started getting really cranky and I couldn't figure out why.  I thought teething too cause she's chewing on everything including me.  I ended up observing her carefully and writing everything down and called her doctor.  In the end she wasn't teething yet but has acid reflux.  I do have some friends though who's babies began teething at 3 months.  I hope this helps!