Taken Directly From The Desk of Lemmy (his facebook):
Regretfully, Motörhead announces it has had to cancel its remaining six summer festival appearances. The band hate to let their fans down by missing any shows, but they expect to be back in full force this Fall.
As you may have heard, earlier this Spring Lemmy had some medical maintenance for the long-term good, He was, at that time, advised to rest, but once feeling better, he of course resumed his life as usual. He has since been advised that he should immediately take some more time to rest
Lemmy says: I'd like to thank everyone who wish me well, it was a tough decision for me as I don't like to disappoint the fans especially in times where economy is bad and people spent their money to see us. But sometimes you can't do anything else than following doctor's orders, but be sure we will be back and kick everybody's ass.
There you have it! You can now stop worrying, redirect those cards, flowers and chocolates to a loved one (who will appreciate them far more), keep calm and carry on! Lemmy and Motörhead certainly are! Thanks and see you in the Fall for their new album in the form of a massive Aftershock...