Quite recently, on October the 4th, QTUM Ignition (mainnet blockchain) was launched, and an auto-swap was arranged via main exchanges, so that QTUM ERC20 holders could swap their tokens for the new coin.
Coinomi users who were informed of this and sent their QTUM to one of the participating exchanges for the auto-swap, have already gone through the process and must have received their new QTUM coins in their new exchange addresses, for example, in Bittrex: https://support.bittrex.com/hc/en-us/articles/115001606011
Coinomi users who swapped their QTUM to any other asset prior to October 4th should also not be concerned. The following concern Coinomi users who still hold QTUM ERC20 tokens in their Coinomi ETH wallet: Coinomi does not support the new main net at the moment, it will do at a later date.
Thankfully, QTUM team partnered with Changelly exchange, in order to provide users who missed the auto-swap in exchanges, a way to still swap their tokens for the main coin. Moreover, this will last for three whole months.
Users are advised to go to the dedicated Changelly QTUM swap page - https://qtum.changelly.com/ and follow the step by step process.
You will need etiher a new, mainnet QTUM address from a supporting exchange, or the desktop wallet for your platform, downloadable here: https://github.com/qtumproject/qtum/releases.
Changelly will require an Ignition QTUM address (from either a supporting exchange or the desktop wallet) in order to send the swapped coins back to you.
Then it's simply a matter of sending your QTUM ERC20 tokens from Coinomi to Changelly's provided address in the next step.
Remember that to send your QTUM tokens to Changelly you need some ETH in your Coinomi ETH wallet as the tokens themselves cannot be used to pay for gas (fees) for the transaction.