What can be the cause of loud thumping noise coming from my front end?

You would have had to skid for a pretty good distance to wear a flat spot on the tire. Are the tires old? Could have shifted a belt in the tire, or lost a wheel weight, causing your vibration. The noise only started after the skid?

The short naswer is yes, when you skidded, you wore a flat spot on the tire, this causes the thumping noise that should follow the speed of car. It should be slow at slow speeds and faster at faster speeds... The vibration is caused because the tire is now out of balance because of the missing rubber where you skidded... I know this from experience, my son pulled the E-brake on a brand new car and I fought with the dealer for 3 months before he admitted skidding to a stop from 60 mph and wearing the flat spots...