Hello everyone - hoping for some advise
Background: been keeping sheep for about 8 years, various breeds and have encountered all sorts of issues and illnesses as with all flocks! Today we've had a death that has baffled me some what and I'm hoping someone may be able to help

?
Ewe: 9 year old pure bred Wiltshire horn, just lambed 4 weeks ago (lambs doing great) on heptivac system and all wormed with a complete four stage fluke control, calcium and selenium supplement and feet done. Great body condition, if anything maybe a bit too fat! Full mouth but not broken. On rough grass and some marshy land at the moment - all flocks looking great and lambs growing well
Symptoms - slightly quiet and separate for the last couple of weeks but still eating and feeding lamb. She has always kept herself to herself so this isint out of character although we have noticed her laying down rather a lot and a bit lack luster to move ... but with a couple of bellows ...shes been straight up for lunch
Saw her yesterday eating in field, today she was dead where they sleep at night under a tree, laying on side, head in air, white foam out of mouth, blood from eyes and ears but no damage to eyes from crows. Very bloated and gassy:stomach was solid with gas.
No injury and at this stage I can see no reason for death. She's an older ewe and this was going to be her last lamb anyway. She's my favourite, so whilst upsetting I'd really like some help in working out the issue.
Thanks again!
Josh from Scarletts Farm (22 years old) based in essex