You're not being DDOSed but you are probably compromised, part of a botnet or being used for DNS amplification attacks or any combination of them.
You need to have a read of the manual -
https://help.mikrotik.com/docs/spaces/R ... 574/Filter
Firstly though:
Disconnect your WAN interface from your router.
Remove all your current firewall rules, Raw and NAT included.
Sort out your interface lists with WAN and LAN and here's an example of a default firewall configuration.
/interface list member add list=LAN interface=bridge comment="defconf"
/interface list member add list=WAN interface=ether1 comment="defconf"
/ip firewall nat add chain=srcnat out-interface-list=WAN ipsec-policy=out,none action=masquerade comment="defconf: masquerade"
/ip firewall
filter add chain=input action=accept connection-state=established,related,untracked comment="defconf: accept established,related,untracked"
filter add chain=input action=drop connection-state=invalid comment="defconf: drop invalid"
filter add chain=input action=accept protocol=icmp comment="defconf: accept ICMP"
filter add chain=input action=accept dst-address=127.0.0.1 comment="defconf: accept to local loopback (for CAPsMAN)"
filter add chain=input action=drop in-interface-list=!LAN comment="defconf: drop all not coming from LAN"
filter add chain=forward action=accept ipsec-policy=in,ipsec comment="defconf: accept in ipsec policy"
filter add chain=forward action=accept ipsec-policy=out,ipsec comment="defconf: accept out ipsec policy"
filter add chain=forward action=fasttrack-connection connection-state=established,related comment="defconf: fasttrack"
filter add chain=forward action=accept connection-state=established,related,untracked comment="defconf: accept established,related, untracked"
filter add chain=forward action=drop connection-state=invalid comment="defconf: drop invalid"
filter add chain=forward action=drop connection-state=new connection-nat-state=!dstnat in-interface-list=WAN comment="defconf: drop all from WAN not DSTNATed"
Connect up your WAN again and test your internet access. Then you can move on to your NAT rules.