If you were due to sign on 19th, regardless whether you attended the JCP afterwards or not, your last payment date will be the 5th, the last time you signed.
As an added note (from a JCP keyboard rattler as Dizzynita calls us ) you are allowed 2 separate periods of sickness, each up to 14 days. If for example your date of claim was 01.10.10, you are allowed 2 periods of sickness between 01.10.10 and 30.09.11. Anything longer than 14 days, then you need to make a claim for ESA.