I have several PC's, laptops tablets and smartphones.
All show download speeds of around 45Mbps and all show uploads of around 8Mbp, EXCEPT one tablet (Samsung S3) which suddenly started to alternate upload between 0.06/0.10, whereas it had been the same upload as the others.
Samsung S3 is a smartphone, not a tablet. Are all your devices using the same gateway? As wee eddie says maybe something you installed has changed your phone connectivety speed. Maybe you accidentally gave permissions to some/several apps to connect and they are abusing the privilege?