Can allergies create "cold/flu" like symptoms? ive been having a lot of congestion and phlegm for the past 4 days but doesnt seem to be coming from my lungs. allergies

Yes it can: And don't need to come from lungs,upper respiratory passages can produce lots of secretions. When you have allergies/prone to,viruses can trigger symptoms, without having an infection, saline nasal washes and regular intake of antihistamines & decongestants,unless contraindicated,can help,pls read the labels carefully and don't exceed recommended dosage and duration, if no improvement c ur doctor