First off, what I've heard there is no Dogecoin fork. Some are confused and still think there be a fork, originally to have a Dogecoin Ethereum Bridge. They already made one without a forking the blockchain.
Now the theory. I think the reason Dogecoin is skying right after the Ethereum Bridge is because someone one is planning to put in DApp using dogecoin with Ethereum DApp and they plan that it will be very successful. I don't think the surge is a coincidence right after the bridge was created. If u expect such an Dapp to come out before the year is out, expect copycats afterwards.
Another theory is maybe it is just a coincidence, someone is paying their workers in Dogecoins and at the same time, selling them merchandise that accepts Dogecoin. Maybe there is a hidden economy, we don't know about - someplace where currency is not working well.
** Disclaimer This blog is based on my opinions. I am not giving professional advice. Anything written here should be taken as an opinion and is the responsibility of the reader to take due diligence as such. Basically saying I may be wrong, right or neither, just saying its my opinions and my voice.