domain: domain1.com
    domain: domain2.info
    domain: domain3.com
dataamount: 9210470
    domain: domain4.com
    domain: domain5.com
    domain: domain6.com
dataamount: '25325235235'
    domain: domain7.com
    domain: domain8.com
dataamount: 12321

domain: domain1.com
    domain: domain2.info
    domain: domain3.com
dataamount: 9210470
    domain: domain4.com
    domain: domain5.com
    domain: domain6.com
dataamount: '25325235235'
    domain: domain7.com
    domain: domain8.com
dataamount: 12321

domain1.com,  domain2.info,  domain3.com,
dataamount: 9210470
 domain4.com,  domain5.com,  domain6.com,
dataamount: '25325235235'
 domain7.com,  domain8.com,
dataamount: 12321

perl -pe 's#^s+domain: (.*)n$#1, #;s#(dataamount.*)$#n1#' file.txt