Hey there antheab and welcome here!
You could have quite a few problems so maybe we can narrow them down. Buffer Problems
Your Running buffer (for running gels) may be the source of your problem (pH or salt problem)
Your lysis buffer (new source of tissue? Cells?) may be the problem due to changes in salt or lysis conditions.
Are you sure you are using the right percentage of polyacrilamide gel? (maybe you are running higher percentage by accident? Gel Running Problems
Did you check your voltage? current? Is it the same as before? IEF / Agarose
Last but not least, your agarose and/or IEF buffers may be affecting the proteins and the way they run.
Sorry for the long list. Just narrow it down!
Please post back here so we can continue helping you and find out what solved your problem... dont leave us in agony!